Re: Entity and Identity

Walter Mitty wrote:
> I intended no pugnacity in my response.

No, and I'm sorry I left that inference. I was referring to earlier messages in the thread, where anyone who even mentions the word "object" gets jumped on.

My comment about not reading clearly was because I wrote to draw the very same distinction you reinforced. The fact that o-o programmers don't use mathematically pure notions doesn't appear to stop them producing functional systems, and it doesn't mean that all the concepts of object orientation are useless and wrong, which seems to be the mood here.

> For a variety of reasons, I prefer the word "representation" to
> "instantiation". And, in the cases you outlined, what we have is not
> multiple representations of the same tuple, but multiple copies of the same
> representation. It's inherent in data that data can be copied. A lot of
> (real world) objects cannot be copied. Managing data in such a way that the
> multiple copies of the same representation of a tuple are bound together in
> some fashion that relates to ACID is not a pretense, by any stretch of the
> imagination.

Well, that's a fair clarification. By "pretense", I mean that we can pretend that the object is not even being copied. That pretense is not possible with almost any o-o system, which gives the lie to Brian's assertion that location is part of state. In other words, I wrote to support your side of the argument.

--
Clifford Heath, Data Constellation, http://dataconstellation.com
Agile Information Management and Design